Pathological laughing and eying in multiple sclerosis: a preliminary report suggesting a role for the prefrontal cortex

As part of a wide ranging study investigating the prevalence, demographic a nd disease related characteristics of pathological laughing and crying (PLC ) in multiple sclerosis (MS), a putative role for the prefrontal cortex was also explored Eleven multiple sclerosis (MS) patients with carefully defin ed PLC were compared to a control group of 13 MS patients without PLC on va rious cognitive indices known to be sensitive to frontal lobe dysfunction. Although the two groups did not differ with respect to age, sex, physical d isability, disease course, duration of MS, years of education, premorbid IQ and depression, the PLC group performed more Poorly on the Stroop test and a measure of verbal fluency. They also showed a trend to make more total e rrors on the Wisconsin Cord Sort Test The relevance of these findings to th e pathogenesis of PLC is discussed in particular whether the syndrome is, i n Port mediated by dysfunction of the prefrontal cortex.